These things are amazing. We didn't want to deal with traditional sippy cups after realizing my 5 year old neice still cant (or wont) use a regular cup and demands a sippy cup or at bare minimum a straw. Our little guy had a bit of a hard time figuring these out but hes 7 months so i expected it. He wanted to chew on rim but after a couple times using it without silicone gasket, he realized what was going on and now is a pro with it. I have to fill it all the way up so he doesnt have to tip his head back to drink so its ends up too heavy for him to hold but as he grows he will be able to do that. I was after evey use so not sure why some people are talking about mold unless they never clean thiers.